Lubricating compositions



Patented Nov. 7, 1944 UNITED STATES PATENT OFFICE."

LUBRICATING SITIONS Louis A. Mikeska, Westfield, N. J., assignor to; Standard Oil Development Company, a corporation of Delaware Application December 16, 1938, Serial N0. 246,073

No Drawing.

24 Claims.

This invention relates to improved oxidation inhibitors which are particularly eifective in mineral oils-and lubricating compositions, particularly to metal derivatives of phenol sulfides.

It has been found that both the stability and lubricating properties of hydrocarbon oils are improved by adding thereto small amounts of metal derivatives of phenol sulfides. These compounds include metal salts of phenol sulfides which are represented by the following formula:

' in which M represents a metal, such as aluminum, barium, calcium, cobalt, chromium, magnesium, manganese, sodium, nickel, lead, tin, zinc, copper, iron, cadmium, potassium, lithium andthe'like. In the case of polyvalent metals, other valences than that connected to the oxygen in this formula may be joined to other inorganic or organic groups, such as halogen, sulfur, oxygen, alkyl and aryl groups,- residues. of alcohols, phenolic compounds, mercaptans, organic and inorganic acids, such as OR" and -,S

' and the like, in which R" represents an organic or inorganic group or'radical. R represents an organic group which may be either aryl, alkyl, aralkyl, or alkyl-aryl and which may contain substituent groups, such as halogen, particularly chlorine, also nitro, nitroso, amino, hydroxy, carboxy, alkoxy, aroxy, mercapto, and the like.

R, represents an organic group of the same class as R, and which may also contain the same substituent groups, but is preferably an of about 4 to 8 carbon atoms.

The hexagon represents an aro'matic nucleus containing 1 or more benzene rings or a condensed ring system, such as in naphthalene and the like. The'hexagon may also contain any alkyl group one or more of the substituent groups described in connection with the group R.

The positions of the various groups attached to the hexagon are not limited to those shown above, this formula being merely illustrative, but may also be in any other ortho, meta, or. para relation to each other.

The sulfur atom represented by S in the above formula may be substituted. by selenium or tellurium. The subscript :1: represents an integer between 1 and about 5 and is preferably 1 or 2.

. Metal salts of, alkyl phenol sulfides and polymers thereof have beenlfound particularly efiective improving'agents for lubricating oils. These alkyl phenol sulfides include the following classes:

(01. 252-48) 1. Alkyl phenol thioethers 2. Alkyl phenol disulfldes OH OH and OH OH 3. Polymers of alkyl phenol sulfides 40 While the above compounds are preferably symmetrical, one or more of the benzene nuclei may contain other substituent groups, such as represented by the following formula:

OH NO: I

p s N02 5. Dinitro phenyl alkyl phenol sulfide In all the above Formulae 1' to 5, R represents an alkyl group containing preferably about 4 to 8 carbon atoms.

This invention relates to metal derivatives of all such compounds, in. which the hydrogen of one or more of the hydroxyl groups is replaced by a suitable metal such as those described above. In the case of polyvalent metals, the metal may be connected to two hydroxyl groups of the Same molecule or it may join two diflerent molecules, which may be similar or difierent, at

least one of the molecules being a phenol sulfide.

Illustrative salts are represented by the following formulae:

EXAMPLEI.

1 mole of tertiary amyl phenol thioether (prepared by the method described in the French Patent 824,600) is dissolved in about 1 times its volume of absolute ethyl alcohol. This solution is then added to'a solution of sodium ethoxide, prepared by dissolving 2 moles of metallic sodium in an exces of absolute ethyl alcohol. The sodium salt of the phenol, described as the thioether of tertiary amyl sodium phenolate, is thereby formed and remains in solution in the excess ethyl alcohol.

It may be recovered by evaporation of the alcohol, or the solution may be added directly to a lubricating oil, in which case the alcohol may be removed by evaporation in case a lubricant having a high flash point is desired. 1

Other metal salts may be prepared from the sodium salt by a simple double decomposition reaction which is illustrated in the following example:

Exmm II A slight excess over the calculated amount of the anhydrous halide (chloride or bromide) of the desired metal, such as calcium chloride, is

dissolved in absolute ethyl alcohol, and the resulting solution is added with stirring to the alcoholic solution of the thioether of tertiary amyl sodium phenolate described in the preceding example. The thioether of tertiary amyl calcium phenolate (calcium salt of dialkyl dihydroxy diphenyl sulfide) is thus formed along with sodium chloride, which is insoluble in the absolute alcohol and precipitates therefrom. The mixture is then filtered to remove the precipitated sodium chloride and the alcohol removed by evaporation of the filtrate, the last stage of the evaporation being conducted under vacuum. If it is found that the sodium chloride is not completely removed, due to the presence of traces of water or other reason, the product may be further treated to remove the sodium chloride by any suitable means. For example, the dried product may be dissolved in petroleum naphtha in. the

lute alcohol.

In some cases it will'be found that some of the metal salt of the'phenol thioether precipitates along with the sodium chloride. It may be recovered by extracting the dried precipitate with 54 B. naphtha. The desired product is -then obtained in concentrated form by evaporation of the naphtha. v

Absolute methyl alcohol may also be used as solvent in place of the ethyl alcohol in the same processes described above. It is preferable to methyl alcohol as a solvent in the preparation of the corresponding nickel salts of phenol thiiethers, as nickel chloride is only slightly soluble in ethyl alcohol.

EXAMPLE III -Thioether phencintes of metals having suiliciently basic oxides may be prepared by a direct reaction of the phenol thioether and the oxide in the following manner: A mixture of 107 parts of tertiary amyl phenol thioether, 214 parts of xylol, 10.8 parts of water, and 16.8 parts of hydrated calcium oxide was heated to boiling under a reflux condenser provided with a trap for removing water from the reflux condensate. The refluxing was continued until all the 'water (16.5 parts) had been removed. There was thus obtained an xylol solution of the thioether of tertiary amyl calcium phenolate (calcium. salt of diamyl dihydroxy diphenyl sulfide). The excess calcium oxide (or hydroxide) was insoluble in the xylol and was removed by filtration. The calcium salt of the tertiary amyl phenol thioether was then obtained by evaporation of the xylol from the filtrate. I i

This process may also be conducted with other basic oxides or hydroxides, such as those of barium, sodium, potassium etc.

EXAMPLE IV 7 was then added to the resulting suspension of magnesium ethoxide. The mixture was refluxed for 24 hours and was then filtered while hot to separate insoluble material. The filtrate was r then evaporated to dryness and there was realcohol.

covered as residue the thioether of tertiary amyl magnesium phenolate.

EXAMPLE V One part of anhydrous sodium hydroxide is suspended in 3 parts of 98% strength isopropyl The theoretical amount of tertiary amyl phenol thioether for neutralization of the phenolic hydroxyl groups by the sodium hydroxide was then added. The resultingsolution 'was then heated to boiling and two parts of the Example V.

so long as water is present in the mixture being distilled; There was thusobtained a solution of the thioether of tertiary amyl sodium phenolate in absolute isopropyl alcohol.

Salts of other metals'may be prepared by using the halides of such metals as described in Example II. For example, the theoretical amount of anhydrous calcium chloride is added to the distillation residue and the suspension heatedunder reflux until the calcium chloride has all reacted. The precipitated sodium chloride is then removed by filtration and the thioether of tertiary amyl calcium phenolate is obtained as a residue by evaporation of the isopropyl alcohol. pther metal halides 'may be used in.place of the calcium chloride, for example, barium bromide, lithium chloride, or any other metal halide which is soluble in dry isopropyl alcohol.

;EXAMPLEVI 100 parts of benzene are added to 100 parts of 95% alcohol containing 25 parts of tertiary amyl phenol thioether and enough sodium hydroxide to neutralize the latter. The resulting solution is heated to boiling and water removed -in the constant boiling mixture benzene-wateralcohol which distills over. Thereafter anhydrouscalcium chloride is added to the distil-- lation residue, which is an anhydrous solution in benzene and alcohol and the reaction is com-v pleted in the same manner as-in Example V.

A solution of calcium chloride in 95% ethyl alcohol'may be used, instead of anhydrouscalcium chloride, in which case the water present in the alcohol is removed by further azeotropic distillation. After removal of the water, the

preparation of the thioether of tertiary amyl calcium phenolate is'completed as described in Corresponding metal salts of alkyl phenol disulfide and polysulfides and of the polymers,

tion inhibitors generally in organic materials which are subject to degradation by oxidation during normal conditions of storage or use, or

' which tend to deteriorate by absorption of oxygen from the air. Illustrations of such materials are: fatty oils, petroleum oils and their derivatives, soaps, aldehydes, synthetic resins, rubber, synthetic rubber; paper and the like.

These compounds greatly improve mineral lubricating oils including the highly refined oils such as synthetic oils, solvent extracted Oils obtained by treatment of mineral lubricating oils with single solvents suchas phenol, dichlorethyl ether, furfural, propane, nitrobenzene, crotonaldehyde, etc., or by double or multiple solvents reagents, and adsorptive agents; as well as coal tar or shale distillates, pale oils, neutrals, bright stocks and other residual tocks, cracking coil tar fractions, condensed or polymerized fractions, and the like, either waxy, dewaxed, or nonwaxy. They are especially desirable for addition to crankcase lubricants used in internal combustion engines and to other lubricants which are used atelevated temperatures aboveabout 150 to 200 C. V

The lubricants and other oxidizable organic materials to which these improving agents are 40 added niay also containdyes,- metallic or other such-as the dimers, trimers, and tetramers of the alkyl phenol thioethers, disulfldes, and polysulfldes, may also be prepared by substituting the respective alkyl phenol sulfide for the alkyl phenol thioethers used in the above examples. Metal salts of the corresponding selenides and tellurides may also be prepared by similar methods. 1

The crude products may also, if desired, be

' subjected to further purification in addition to,

or in combination with or in place of the distillations described above. Preparation of products 'of enhanced purity may be accomplished by fractional crystallization, by extraction or precipitation with selective solvents. Impurities may also be removed by treatment with suitable adsorptive agents, such as clay.

While these compounds, or mixtures. thereof with other members of the same class and with the corresponding alkyl phenol sulfides.- may be added in any desired concentration within their solubility limits to lubricating oils, they are preferably used in' concentrations of about 0.01 to 2.0%; a concentration lot about, 0.05 or 0.1 to 0.25% will be found suflicient to stabilize the majority of petroleum lubricating oils. Larger proportions of about 5% or more may be used to improve the lubricating properties of the oil.

The compounds described above may be used as oxidation inhibitors and improving agents in similar concentrations in' other hydrocarbons, such ,,as waxes, 'fueloils. Diesel oils, naphthas, burning oil, gasoline, and the like. Y

7 These compound may also used as oxida- 76 soaps, pour inhibitors, sludge dispersers, oxidation inhibitors, thickeners, V. I. improvers such as soluble linear polymers, oiliness agent's, resins, rubber, fatty oils, heat thickened fatty oils, sulfurized fatty oils, extreme pressure lubricating. agents, organo-metallic compounds, bright stocks (such as refined petroleum lubricating oil residues), 'voltolized fats, mineral oils and/or waxes, colloidal solids such as graphite, zinc oxide, etc., and the like.

The following examples illustrate the use of these compounds in the preparation of improved lubricating compositions.

EXAMPLE VII A naphthenic petroleum lubricating-oil ha a viscosity of 55 seconds ,Saybolt at 210 F. was

- blended with 1.0% of the thioether of tertiary emyl calcium phenolatelprepared as described in Example II above) Diesel .oil oxidation tests on the original oil "and the blend gave the following results:

I Diesel oil oxidation tests 011 4 1m: vziirsjosms.

Blankoi] 1 '2 4 Blank oil +l%inhibitor 1 1 1 ,Diesel oiloxidation test.

The oil is oxidized at 300. F.- -Ior the number of hours indicated. A 10 gram sample is removed and filtered through paper. The deposit left on the paper is rated from 1 to 1 representing a'minimum of deposit and 10 a maximum.

EXAMe LE VIE Blends of the same.oil used in the preceding oil. The results are given in the following table:

Sligb test Oil mgs. of

sludge Blank oil 61 Blank oil calcium inhibitor 32. 7 Blank oil aluminum inhibitor 21. 9

Sligh test This test of the tendency of an oil to sludge under oxidizing conditions is described in Proc. A. S. T. M. 24, 964, II (1924), exceptthat the oxidation was conducted for 24 hours.

EXAMPLE IX Blends of various metal salts of tertiary amyl phenol thioethers prepared by the methods described above in 0.25% concentration in a re-- fined paraffinic petroleum lubricating oil having a viscosity of 77 seconds Saybolt at 2.10" F. were compared with the original oil by using the oil and the blends thereof as the crankcase lubricant .in runs made under closely comparable conditions in a' C. F. R. (Cooperative Fuel Research) engine. After each run the engine was taken down, inspected, and rated by demerits according to the condition of the piston parts, valves, and cylinder. On the scale used, the demerit rating of the blank oil is taken as 100. The reference rating for the blends is expressed as a ratio Blend demerits Blank oil demerits On this scale the numerical rating is lower as the engine condition is better. The runs were each made for 14 hours at a jacket temperature oi 375 F. The. results are given in the following table:

G. F. R.

Oil test percent ofreferencc Blank oil 100 Blank all aluminum salt 24 Blank oil barium salt 10 Blank oil calcium salt 17 Blank oil nickel salt 12 Blank oil cobalt salt 9 in which the groups R, OM, and M are all connected to the aromatic nucleus, and M represents a. metal, R and R represent organic groups or H, Z represents a member of the sulfur family,

and x represents an integer, 1 to 5.

. 2. Improved lubricant comprising a hydrocar bon lubricating oil and a small proportion of a compound having the formula tertiary amyl phenol sulfide.

awmo-mrowmn' in which the groups R, DM, and S are all con-- nected to the aromatic nucleus, and M represents a metal, R and R represent alkyl groups oi. 4 to 6 carbon atoms each, and :1: represents an integer, l. to 5.

3. Improved lubricating oil composition comprising a hydrocarbon lubricating oil and a small proportion of a sulfide of a metal phenolate.

4. A composition as in claim 3 wherein the metal is calcium.

5. A composition as in claim 3 wherein the metal is tin. 6. A lubricating oil composition comprising a major amount of a. hydrocarbon lubricating oil and a minor amount of the calcium salt of an alkyl phenol sulfide in which the alkyl groups each contain between four and eight carbon atoms.

7. A lubricating oil composition comprising a major amount of a hydrocarbon lubricating oil and a.minor amount of the calcium salt of a 8. Improved lubricating oil composition comprising a hydrocarbon lubricating oil and a small proportion of a thioether of a. metal phenolate.

9. Improved lubricating oil composition comprising a hydrocarbon lubricating oil and a small proportion of a disulfl'de of a metal phenolate.

10. Improved lubricating oil composition comprising a hydrocarbon lubricatingoil and a small proportion of a sulfide of a metal phenolate containing an alkyl group connected to the arcmatic nucleus.

11. Composition according to the preceding claim in which the said alkyl group has from 4 to 8 carbon atoms.

12. Improved lubricating oil composition comprising a hydrocarbon lubricating oil and a small proportion of a metal salt of amyl phenol thio ether.

13. Improved lubricating oil composition com-,

prising a hydrocarbon lubricating oil and a small proportion of a metal salt of amyl phenol di- 14. A lubricant comprising a major proportion of a mineral lubricating oil having dissolved therein a small amount of a sulfide of a metal salt of an alkylated aryl compound having a hydroxy group attached directly to the aromatic.

, nucleus.

. 15. A lubricant according to claim 14 in which the sulfide of the metal salt is an oilsoluble metal salt of the reaction product of a sulfur halide with an alkylated'aryl compound having a hydroxy group attached directly to the aro- 'of a compound having the general formula.

groups or H, Z represents a member of the sulfur family, and :2: represents an integer 1 to 5.

17. Alubricating oil composition comprising a major proportion of a hydrocarbon lubricating oil and a small proportion of a compound having the general formula R(OM)A1'Z2R', in which Ar is an aromatic nucleus and in which the groups R, OM, and ZIR are all connected to the aromatic nucleus, and M represents a metal, R and R represent organic groups or H, Z represents a member of the sulfur family, and a: represents an integer 1 to 5. Y

18. Improved lubricating oil composition comprising a paraflinic petroleum lubricating oil having dissolved therein a small proportion ofa soluble sulfide of a metal phenolate having an alkyl group connected to the aromatic nucleus.

19. Composition according to claim 15in which the said alkyl group has from four to eight carbon atoms.

20. Composition according to claim 14 in which the said metal is calcium.

21. An improved mineral oil composition comprising a mineral oil having admixed therewith a minor proportion of an oil miscible sulfide of an alkyl substituted aryl metal oxide in which the oxygen of the metal oxide group is directly attached to the aryl nucleus and in which at least two alkyl substituted aryl nuclei are interconnected by; at least one atom of sulfur.

' compound having the formula in which the groups R, OM and SIR are all conand a minor amount of the metal salt of an oilsoluble aliphatic substituted phenol sulfide, each aliphatic radical containing at least four aliphatic carbon atoms.

24. An improved mineral lubricating oil composition comprising a mineral lubricating oil LOUIS A. MIKESKA. 

